JPH0127340Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a single-chip color television camera.
A first color difference signal is obtained from the horizontal scanning line, a second color difference signal is obtained from the second horizontal scanning line, and a low frequency signal is obtained by removing the high frequency signal contained in the solid-state image pickup plate output signal with a low pass filter. is used as the luminance signal,
The present invention also relates to a color-difference sequential color television camera that obtains a color signal of a color television signal using the two color-difference signals.

In recent years, various proposals have been made for single-chip color television cameras that obtain color television signals by using one solid-state image pickup plate and one mosaic or striped color filter.

As an example, the outline of patent application No. 126592 (1977) is given in the first section.
This will be explained using FIGS. FIG. 1 shows the arrangement relationship between the mosaic color filter and the photosensitive area of the image pickup plate. Reference numeral 1 denotes a mosaic color filter, which is composed of a red filter R, a blue filter B, and a luminance characteristic filter Y arranged as shown in the figure. 2
A large number of photosensitive sections are arranged vertically and horizontally on the image pickup plate, and the photosensitive sections 2 and the R, B, and Y color filters correspond to each other. The R or B color filter portion spanning the light-receiving pixels of adjacent horizontal lines is for equalizing the low-frequency signal amount of the image pickup plate output signal for each horizontal period, and as shown in FIG. When the interval between the color filters 2 and 2 is narrow, such a configuration of the mosaic color filter 1 is suitable in view of the filter dimensions.

As is well known, the R filter is a low pass filter, and the B filter is a low pass filter.
The filter is a high-pass filter, and the Y filter is a band-pass filter. FIG. 2 shows the spectral characteristics of general R, B, and Y color filters. The signals obtained by associating the color filters shown in FIG. 2 with the light-receiving pixels of the image pickup plate will now be described. To simplify the explanation here, we will focus on the visible range (wavelengths from 400 to
700 mm) is assumed to be flat, and the ratio of two types of color filters corresponding to each photosensitive section 2 is 2/3:1/3.

With such a combination, for (n) ₁ H in the first field, (2/3R + 1/3B), (2/3Y +
1/3 B)..., in the first field (n+1) ₁ H, (2/3B+1/3R), (2/3Y+1/3R),...
, in the second field (n) ₂ H, (2/3R + 1/3B), (2/
3Y +1/3B),..., in the second field (n+1) _2H , (2/3B+1/3R), (2/3Y+1/3R)...
dot sequential signals are obtained sequentially and alternately. Here, for example, a schematic diagram of the image pickup plate output signal when an image of a subject with a cyan color is taken is as shown in FIG. 3 with B being the winner.
In FIG. 3, A indicates the column of the first field (n) ₁ H, and B indicates the column of the first field (n+1) ₁ H. A block diagram for converting this signal into a standard color television signal is shown in FIG. In FIG. 4, numeral 3 is a solid-state image pickup plate that combines the mosaic color filter shown in FIG. There is. At the same time, the image pickup plate output signal is passed through a bypass filter 5 centered at a frequency corresponding to the array period of the mosaic color filter, and only the fundamental wave component spatially modulated by the mosaic color filter is separated.
By performing synchronous detection in the synchronous detection circuit 6, color difference signals (R-Y) and (B
-Y), and after passing this signal through a low-pass filter 7, it is supplied to a switch circuit 9 via a delay line 8 for one horizontal period. An undelayed signal is also supplied to the switch circuit 9 at the same time, and the input signal is switched every horizontal period. Through the above operations, the line-sequential color difference signal is converted into two consecutive color difference signals, which are then supplied to the color encoder 10 and operated with the luminance signal to obtain a standard color television signal. Note that the output signal from the pulse generator 11 is applied to the solid-state imaging plate 3 to drive it, and pulses in a synchronous relationship therewith are also supplied to the synchronous detector 6, the switch circuit 9, and the color encoder 10.

Here, the output signal per each photosensitive part is 1,
If the ratio of the R and B color filters arranged across the light-receiving pixels of adjacent horizontal lines is each 1/3, the image pickup plate output signal shown in FIG. 1 is (n) ₁ of the first field. H, (n+1) ₁ H, second field (n) ₂ H, (n+1) ₂ H output signals S(n)
₁ H, S(n+1) ₁ H, S(n) ₂ H, S(n+1) ₂ H
is S(n) ₁ H=2/3(R+B+Y) +2/3(R-Y) sinωt S(n+1) ₁ H=2/3(R+B+Y) +2/3(B-Y) sinωt S(n) ₂ H=2/3(R+B+Y) +2/3(R-Y) sinωt S(n+1) ₂ H=2/3(R+B+Y) +2/3(B-Y) sinωt Here, ω is the horizontal direction of the color filter. In such an ideal case, the amount of each color difference signal in the first field and the second field is equal, so that no flicker occurs.

However, in reality, it is difficult to precisely match the positional relationship between the mosaic color filter and the photosensitive portion of the image pickup plate as shown in FIG. If the vertical distance of one pixel is 1, for example, as shown in Figure 5, the mosaic color filter does not overlap relatively adjacent light-receiving pixels arranged in the vertical direction as in Figure 1. (n) ₁ H of the first field,
(n+1) ₁ H and (n) ₂ H of the second field, (n+
1) _Each output signal S'(n) of ₂ H, S'(n+1) ₁ H,
S′(n) ₂ H, S′(n+1) ₂ H is S′(n) ₁ H=[(2/3-K)(R+Y)+2(1/3+K)B]+(2 /3-K)
(RY)sinωtS′(n+1) ₁ H = [(2/3-K)(B+Y)+2(1/3+K)R]+(2/3-K)(BY)sin
ωt S′(n) ₂ H=[(2/3+K)(R+Y)+2(1/3-K)B]+(2/3+K)
(RY)sinωt S′(n+1) ₂ H=[(2/3+K)(B+Y)+2(1/3-K)R]+2/
3+K)(BY)sinωt However, ω is the horizontal repetition frequency of the color filter, and the low-frequency component that is the luminance signal and the (R-Y)sinωt and (B-Y)sinωt systems that are the color difference signals are calculated for each field. This appears as fritz, which significantly impairs image quality. in fact,
Although it depends on the shape of the photosensitive portion of the image pickup plate, the above-mentioned flicker occurs even with alignment accuracy of about ±2 μm with the current shape and dimensions of the photosensitive portion.

Furthermore, the pitch per pixel of a practical solid-state image sensor is approximately 23 μm in the horizontal direction and 14 μm in the vertical direction, of which the dimensions of the light-receiving pixel are approximately 8 μm in the horizontal direction and 7 μm in the vertical direction. It is not easy to manufacture a color filter that maintains the relationship between the light-receiving pixel and the color filter. In particular, it is necessary to align the color filter elements R, B, and Y with high precision, making it difficult to manufacture such a filter.

In view of the above points, the present invention provides a mosaic color filter that can be easily aligned with the photosensitive portion of an image pickup plate.

To this end, the present invention provides a predetermined low-pass characteristic,
The first to fourth color filters each having different spectral characteristics having high-pass characteristics or band-elimination characteristics are configured in a single layer filter structure, and the first field, the second
a first horizontal row of color filters in which the first and second color filters are arranged alternately for obtaining field signals; and the third and fourth color filters for obtaining signals of the first field and second field. A second horizontal row of color filters in which color filters are arranged alternately is arranged in a vertically repeating manner, and the sum of the color light of the three primary colors passing through the first horizontal row of color filters and the second color filter A mosaic color filter, in which the sum of the three primary color lights passing through the horizontal rows is equal, is arranged corresponding to each light-receiving pixel of the solid-state image pickup plate, and a signal obtained by removing high-frequency signals from the output signal of the solid-state image pickup plate is obtained. a first color difference signal from the first horizontal row of color filters and a second color difference signal from the second horizontal row of color filters are obtained directly and alternately as a luminance signal, with their phase components being equal; The apparatus is configured to obtain a color television signal free of flicker from a luminance signal and a color difference signal.

An embodiment of the present invention will be described below based on the drawings. First, the color difference sequential type mosaic color filter and the photosensitive section of the image pickup plate will be explained using FIG. 6. FIG. 6 is a line diagram showing the relationship between the arrangement of mosaic color filters and the photosensitive areas of the image pickup plate. In FIG. 6, 21 is a mosaic color filter, and 22 is a photosensitive section arranged on an image pickup plate. The mosaic color filter 21 is composed of filter ties, B, C, and D, each having a different spectral property. The horizontal rows of color filters are arranged in an alternating manner. Here, the mosaic filter ties B, C, and D must have the same function as the mosaic color filter shown in FIG. That is, the spectral characteristics of the mosaic color filter ties, B, H, and D are as follows: (A) = 2/3R + 1/3B (B) = 2/3Y + 1/3B (C) = 2/3B + 1/3R (D) = 2/ If 3Y+1/3R, then the mosaic color filter in FIG. 1 and the mosaic color filter in FIG. 6 will have the same function.

Examples of the spectral characteristics of the mosaic color filter ties B, C, and D are shown in FIGS. 7A, B, C, and D, respectively.

As is clear from FIG. 7, the filter tie is composed of a band elimination filter and a low pass filter, the filter filter is composed of a high pass filter and a low pass filter, the filter is composed of a band elimination filter and a high pass filter, and the filter tie is composed of a combination of a low pass filter and a high pass filter.

Next, an example of a method for making an organic filter (gelatin dyed with a dye) having a spectral characteristic of (a) = 2/3R + 1/3B among the color filters described above is shown in Figs. 8 and 9. I will explain. FIG. 8 is a sectional view of the filter where (A)=2/3R+1/3B. The method for making this filter is to first form a magenta filter 24 having R+B spectral characteristics on a glass substrate 23, and then
4 is covered with a protective film 25, a yellow filter 26 is formed thereon, and after the yellow filter 26 is further covered with a protective film 27, a cyan filter 2 is formed thereon.
8 is formed, and a protective film 29 is formed thereon.

Here, the protective films 25, 27, and 29 transmit all colors. Figure 9A shows the spectral characteristics of magenta filter 24.
Shown below. Further, the spectral characteristics of the yellow filter 26 can be arbitrarily obtained by changing the concentration of the dye of the yellow filter, each of the spectral characteristics a to b as shown in FIG. 9B. Regarding the spectral characteristics of the cyan filter 28, if the concentration of the dye is changed in the same way, the 9th
Spectral characteristics a to b as shown in Figure C can be obtained arbitrarily. This means that the amount of transmission of the blue component contained in the light can be arbitrarily selected depending on the concentration of the dye in the yellow filter 26, and the amount of transmission of the red component contained in the light can be arbitrarily selected depending on the concentration of the dye in the cyan filter 28.

Therefore, the spectral characteristics of the filter shown in FIG.
magenta, yellow, shown in FIG. 9 A, B, and C above;
Since it is the product of the spectral characteristics of each cyan filter,
By appropriately selecting the spectral characteristics of each of the yellow and cyan filters, a color filter of (a)=2/3R+1/3B can be obtained.

In the above-mentioned production example, three types of color filters were stacked, but in the present invention, gelatin is dyed with an appropriate mixture of the magenta, yellow, and cyan pigments. Therefore, in this case, the filter structure is not multilayered as shown in FIG. 8, but has a single layer.

If a solid-state image pickup plate that combines the mosaic color filter obtained in this way and an image pickup plate photosensitive section is used to image a cyan-tinged subject, the output signal of the image pickup plate will be the schematic image pickup plate signal shown in FIG. It can be converted into a standard color television signal by the electrical circuit processing shown in .

Furthermore, even if the relative relationship between the mosaic color filter and the photosensitive area of the imaging plate is shifted upward or downward by K, the output signal in each horizontal scan will be (n)'' ₁ H, (n+1)'' ₁ of the first field. H, second field (n)″ ₂ H, (n+1)″ ₂ H output signals S(n)″ ₁ H, S(n+1)″ ₁ H, S(m)″ ₂ H, S
(n+1)″ ₂ H is S(n)″ ₁ H=2/3(R+B+Y) +2/3(R-Y) sinωt S(n+1)″ ₂ H=2/3(R+B+Y) +2/3(B- Y) sinωt S(n)″ ₂ H=2/3(R+B+Y) +2/3(R-Y) sinωt S(n+1)″ ₂ H=2/3(R+B+Y) +2/3(B-Y) sinωt However, ω is the horizontal repetition frequency of the color filter, and the low-frequency component used as the luminance signal and the 2/3 (R-Y) sin ωt and 2/3 (B-Y) sin ωt components used as the color difference signal are equal for each field. Therefore, no fritzing occurs.

The configuration according to the present invention can be applied to a color difference sequential system using a mosaic color filter and a photosensitive section of an image pickup plate other than the relationship between the mosaic color filter and the photosensitive section of the image pickup plate shown in FIG.

As described above, according to the present invention, flickering due to alignment errors between the mosaic color filter and the photosensitive portion of the image pickup plate is unlikely to occur, so it is not necessary to align their relative positions with high precision, and alignment becomes easy. It also has the advantage that the structure of the mosaic color filter is simple.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the mosaic color filter of the previously proposed color difference sequential method and the photosensitive area of the image pickup plate, Fig. 2 is a spectral characteristic diagram of the color filter of Fig. 1, and Fig. 3 A and B are color difference. A schematic diagram of the image pickup plate output signal in the sequential method. Figure 4 is a block diagram of the signal processing. Figure 5 shows that the positional relationship between the mosaic color filter and the image pickup plate photosensitive area is only K compared to the case shown in Figure 1. FIG. 6 is an explanatory diagram showing the mosaic color filter of the color difference sequential method and the photosensitive area of the image pickup plate to explain the present invention. FIGS. 7A to D are diagrams of each color filter in FIG. 6. FIG. 8 is a sectional view showing an example of the color filter, and FIGS. 9A to 9C are spectral characteristic diagrams of each layer of the color filter. 21... Mosaic color filter, 22... Image pickup plate photosensitive section, 24... Magenta filter, 26...
Yellow filter, 28...Cyan filter.

Claims (1)

[Scope of utility model registration request] first to fourth color filters each having different spectral characteristics having a predetermined low-pass characteristic, high-pass characteristic, or band-elimination characteristic are configured in a single-layer filter structure,
a first horizontal row of color filters in which the first and second color filters are arranged alternately for obtaining signals of the first field and the second field; 3rd and 4th
A second horizontal row of color filters in which color filters are arranged alternately is arranged repeatedly in the vertical direction, and the sum of the color light of the three primary colors passing through the first horizontal row of color filters and the second color A mosaic color filter in which the sum of the three primary color lights passing through the horizontal filter rows is equal to each other is arranged corresponding to each light receiving pixel of the solid-state image pickup plate, and a signal obtained by removing high-frequency signals from the output signal of the solid-state image pickup plate. is used as a luminance signal, a first color difference signal is obtained from the first horizontal row of color filters, and a second color difference signal is obtained from the second horizontal row of color filters, with their phase components being made equal, directly and alternately, respectively; A color solid-state imaging device characterized in that a color television signal without flicker is obtained from the luminance signal and the color difference signal.